Radiation Physics

PV QA 3 - Poster Viewing Q&A 3

TU_11_3220 - Initial Experiences with First North American Deployment of HyperArc Radiosurgery Treatment Planning and Delivery System on the Edge Platform

Tuesday, October 23
1:00 PM - 2:30 PM
Location: Innovation Hub, Exhibit Hall 3

Initial Experiences with First North American Deployment of HyperArc Radiosurgery Treatment Planning and Delivery System on the Edge Platform
E. M. Thomas1, R. A. Popple2, E. Covington1, K. Dempsey3, C. D. Willey1, H. Boggs1, J. M. Markert1, B. L. Guthrie1, K. Riley1, M. Bredel1, and J. B. Fiveash2; 1University of Alabama at Birmingham, Birmingham, AL, 2University of Alabama at Birmingham Department of Radiation Oncology, Birmingham, AL, 3University of Alabama at Birmingham, Birmingham, AL, AL

Purpose/Objective(s): HyperArc ™ (Varian Medical Systems) is a novel treatment planning and delivery system designed to streamline both the planning, imaging, and delivery phases of LINAC-based stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiation therapy (hfSRT) through automation of various aspects of the process. We report here the planning and delivery results and characteristics of the first North American deployment of the system.

Materials/Methods: A HyperArc-enabled treatment planning system was used to create 24 separate SRS and hfSRT plans. Each plan utilized a pre-configured non-coplanar arc array and SRS automatic normal tissue optimizer (NTO) designed to replicate the quality afforded by the previously described UAB linac radiosurgery technique. Additional nested tuning structures were not required. The plans were evaluated according to standard radiosurgery plan quality indices including conformity, gradient, moderate isodose spill, and low dose spill. Plans were delivered to SRS phantom to ensure agreement between dose calculated and dose delivered. Each plan was delivered on an Edge™ linac outfitted with high-definition multi-leaf collimator (HD-MLC) in flattening-filter free mode at dose rate of 2400 MU/s. Optical surface monitoring system (OSMS) was used to independently monitor intrafraction motion. Beam and treatment times were recorded. Results: Prescription dose regimens ranged from 15Gy/1fx to 30Gy/5fx, for a total of 58 fractions. There were a total of 64 treated lesions among the 24 patients (range 0.008 to 20.5cm3; median 0.20cm3). Maximum number of lesions treated in one patient was 13. Median RTOG and Paddick CI were 1.23 and 0.76 respectively. Median GI was 4.68. Median mean brain dose was 1.30Gy. Median beam-on time was 1:51 and median total treatment time including imaging was 12:48. Beam was paused during five of the fractions due to detected patient motion. All treatments were successfully completed. Conclusion: Prescription dose regimens ranged from 15Gy/1fx to 30Gy/5fx, for a total of 58 fractions. There were a total of 64 treated lesions among the 24 patients (range 0.008 to 20.5cm3; median 0.20cm3). Maximum number of lesions treated in one patient was 13. Median RTOG and Paddick CI were 1.23 and 0.76 respectively. Median GI was 4.68. Median mean brain dose was 1.30Gy. Median beam-on time was 1:51 and median total treatment time including imaging was 12:48. Beam was paused during five of the fractions due to detected patient motion. All treatments were successfully completed.

Author Disclosure: E.M. Thomas: Honoraria; Varian Medical Systems. Planning Committee Member; Radiosurgery Society. R.A. Popple: Honoraria; Varian Medical Systems. E. Covington: None. K. Dempsey: None. C.D. Willey: Research Grant; American Cancer Society, NIH. Consultant; North, Pursell & Ramos, PLC, Varian Medical Systems. H. Boggs: None. M. Bredel: None. J.B. Fiveash: Research Grant; Varian Medical Systems. Honoraria; Varian Medical Systems.

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